Kvitova defeated current world No. 1 Victoria Azarenka in last year's final in
Istanbul, which will also play host to this elite eight-player event next
year.

Also on Tuesday's schedule, second-seeded former No. 1 Maria Sharapova will
meet seventh-seeded Sara Errani in a rematch of the 2012 French Open final,
which was won by the big Russian in June.

This week's four-player Group A features the current No. 1 and Australian Open
champion Azarenka, Williams (1-0), Kerber (0-1) and eighth-seeded Li Na, while
Group B boasts the 2004 champion and 2007 WTA Championships runner-up
Sharapova, Radwanska (1-0), Kvitova (0-1) and Errani.

The top-two players in each group will advance to the semifinals, and the
winners will square off in the lucrative finale on Sunday.

Azarenka needs only two wins this week to end the year at No. 1.

The winner of this $4.9 million season-ending event could collect as much as
$1.75 million.